Nb浓度对B_2-Ti_(50)-Al-Nb_x合金相稳定性和弹性的影响  

Effect of Nb on Phase Stability and Elastic Property of B_2-Ti_(50)-Al-Nb_x Alloy

作　　者：许密[1] 曾宪波[2] 陈律[2] 闫坤坤[2] 

机构地区：[1]桂林航天工业高等专科学校机械工程系,广西桂林541004 [2]湖南大学材料科学与工程学院,长沙410082

出　　处：《有色金属》2011年第2期26-31,共6页Nonferrous Metals

基　　金：国家自然科学基金资助项目(50771044)

摘　　要：采用基于密度泛函理论的第一原理赝势平面波方法,计算B2-Ti50-Al-Nbx晶体的能量、电子结构和弹性性质,通过合金形成热和Born稳定性判据考察Nb浓度对B2-TiAl晶体稳定性的影响,并采用Cauchy压力参数(C12-C44)和B/C44比值表征和评判Nb浓度对B2型TiAl合金延性的影响。结果表明,当Nb含量约大于8.0%时,B2-TiAl-Nb合金才稳定存在。B2-Ti50-Al-Nbx合金的稳定性随着Nb合金化浓度的升高而减弱,弹性模量则呈增强趋势。Nb含量为9.375%时B2-Ti50-Al-Nbx合金的延性相对最好,随合金化浓度的增大,B2-Ti50-Al-Nbx的延性整体下降。电子度密度和Milliken电荷占据数的分析有效解释了B2-Ti50-Al-Nbx合金的稳定性变化和Nb强化B2-TiAl合金的原因。Using the first-principles pseudo-potential plane wave method,the electronic structures,energies and the elastic module of B2-Ti50-Al-Nbx crystals are calculated.The stability of B2-TiAl crystals are also investigated by a comparison of the heats of formation and the Born Criterion of stability.The ductile/brittle behaviors of B2-Ti50-Al-Nbx alloys are characterized and assessed by Cauchy pressures（C12-C44） and the ratios of B/C44.The results show that B2-TiAl-Nb alloys are stable existence with Nb content 8.0%,the stability of B2-Ti50-Al-Nbx alloys is decreased with the increase of Nb addition and the strength is obviously enhanced.The ductility of B2-Ti50-Al-Nbx alloys with the alloyed Nb at 9.375% is the optimal,whereas it is decreased with the increase of Nb content.For the effect of strengthening and the stability enhancing of Nb addition a reasonable explain has been given on the basis of the analysis and comparison of the density of states（DOS） and the Milliken charge populations.

关 键 词：金属材料 B2-TiAl-Nb合金 结构稳定性 弹性性质 第一原理 

分 类 号：TG146.2[一般工业技术—材料科学与工程]